The long term objectives of this application are twofold: to provide a clear understanding of the physical mechanisms governing the increases in detection sensitivity demonstrated to date by the proposed methodology and to construct prototype hardware from which commercial high mass detection instrumentation can be designed and manufactured. The specific aim of Phase I research is to explore a promising new technology for detecting high mass ions which does not depend exclusively on kinetic ejection of secondary electrons and does not use excessively high voltages for operation. Recent approaches for improving ion detection sensitivity use post-dynode elements to achieve current amplification. This application addresses the feasibility of improving the yield of secondary negative particles at the ion impacted dynode by altering the dynode surface. By providing a dynode treated to lower the surface work function, advantageous use can be made of the physical and electronic properties inherent in the structure of large biomolecules. Enhanced yields of negative fragment ions and possibly photoemissive or thermionic electrons are expected from dynode surfaces treated with an overlayer of cesium-oxygen. The commercial application for ion detectors based on the proposed techniques would extend not only to magnetic sector and TOF instruments, but quadrupoles as well.